With the advent of computer-controlled printing machines, including word processors and electronic typewriters, the limiting factor on the speed of such machines has shifted from the human operator to mechanical operations performed by the machine itself. Therefore, it has been a goal of the typewriter industry to develop faster and faster printers. Naturally, in order that a printer may print faster and faster, all moving parts must be made of light weight so as to minimize the inertia which must be overcome by motive power means in order that the machine may print.
One expedient which has been commonly adopted in order to lessen the inertia of moving parts is to move the printer mechanism, which may include a hammer and a plurality of character elements, or a rotating ball print element, with respect to the print medium or paper and the platen on which it is supported rather than move the platen with respect to the print element, since, in general, the printer may be made lighter than the platen assembly. To further lighten the inertia of this printer assembly, it has been found desirable to carry the bulk of the inked printing ribbon in a cartridge mounted on the frame of the printing machine and only carry a small portion of it along with the printer. This broad concept is shown in copending applications Ser. Nos. 833,270, filed Sept. 14, 1977, and 833,257, also filed Sept. 14, 1977 as well as U.S. Pat. Nos. 4,047,607 and 4,047,608 to Willcox. The relative motion of the print location with respect to the ribbon supply cartridge necessitates that the leader means conveying the ribbon from the cartridge to the print point and back must be flexible. Such a flexible leader means is the subject of copending application Ser. No. 061,880, filed July 30, 1979. A second version of such a flexible leader is a very important aspect of the present invention as well.
Clearly such a leader, to be successful, must satisfy certain design criteria. It must be sufficiently flexible that it can be flexed back and forth throughout the whole travel of the print location thousands of times without failure. Desirably, it is simply made of inexpensive materials and requires minimal assembly skill or time. It must be so designed as to not permit the delicate inked side of certain typing ribbons (perhaps most notably the so-called single-strike-type) from touching any part of the leader or of the remainder of the ribbon assembly so as to preserve the integrity of its surface.